1. Technical Field
The present disclosure relates to surgical devices having a reusable handle assembly and removable and replaceable components. More particularly, the present disclosure relates to an end-effector force measurement drive circuit suitable for use in a surgical instrument for applying fasteners.
2. Discussion of Related Art
Powered surgical instruments for use in endoscopic procedures are known. Typically, such instruments include a reusable handle assembly, and a replaceable and generally disposable component sometimes referred to as single use loading unit or SULU. An adapter assembly connects the loading unit, which can include an end effector for interacting with tissue, to the handle assembly. In the case of a surgical stapler, the end effector can include a replaceable cartridge that is changed after each firing of the surgical stapler. To reduce costs and shorten procedure times, the handle assemblies are generally configured for use with a variety of loading units and/or assemblies of various configurations for use on tissue having different properties, e.g., thickness and density. For example, the different loading units may have staples of different sizes and/or the staples may be arranged in different configurations. To ensure the handle assembly is programmed to operate with the attached loading unit, some loading units are provided with an integrated circuit, also known as a chip, that communicates with the handle assembly to identify the configuration of the loading unit. This arrangement enables the configuration of the loading unit to be automatically conveyed to the handle assembly upon attachment of the loading unit to the adapter assembly, thereby eliminating user error or incompatibility that may be experienced when switching between loading units with different configurations.
Surgical staplers are commonly used for stapling tissue within a body cavity where the end effector is likely to come in contact with fluids, e.g., blood, bile, and/or irrigation solutions. If the interconnections between the chip and the handle assembly are compromised, the chip could malfunction or data communications between the loading unit and the handle assembly could be disrupted, rendering the surgical stapler unstable or inoperable.
Printed circuit boards (PCBs), sometimes referred to as printed wiring boards (PWBs) or etched wiring boards, are widely used in the assembly of discrete electrical components into operating circuits. PCBs generally provide a reliable and economical means of interconnecting electrical signals among system components. PCBs are available in a variety of different types and may be classified in a variety of ways.
PCBs are generally used to mechanically support and electrically connect electronic components using electrically-conductive pathways or signal traces that conduct signals on the PCB. A typical PCB includes one or more layers of insulating material upon which patterns of electrical conductors are formed. In addition to a pattern of conductive traces on the PCB, a patterned array of metal-filled through-holes, or vias, may be formed to allow for layer-to-layer interconnections among various conductive features. A PCB on which electrical components are mounted is sometimes referred to as a printed circuit assembly (PCA) or a printed circuit board assembly (PCBA).
Various kinds of electrosurgical devices that employ PCBs have become thin and/or compact. In some devices, the amount of space needed to accommodate the PCBs may make it difficult to reduce the size of the devices. In some cases, PCB layouts large enough to accommodate the electrical components needed to provide desired functionality and/or performance may increase the overall size of the device and potentially hinder usability.
Electrical signals may be used on PCBs for controlling the delivery of surgical staples to tissue. Surgical devices for applying staples, clips, or other fasteners to tissue are well known. Endoscopic surgical devices for applying surgical fasteners include an actuation unit, i.e., a handle assembly for actuating the device and a shaft for endoscopic access, and an end-effector assembly disposed at a distal end of the shaft. Certain of these devices are designed for use with a replaceable loading unit which includes the end-effector assembly and houses the staples or fasteners. The replaceable loading unit may include staples of various sizes and the staples may be arranged in one or more configurations. After firing the stapler with a replaceable loading unit, the user may remove the empty loading unit, select and attach to the stapler another loading unit having staples of the same or different size and the same or different staple arrangement, and fire the stapler again. This process may be performed repeatedly during a surgical procedure.
During a surgical procedure, when the end-effector assembly is clamping down on tissue, or firing, in some situations it may be unclear whether the end-effector assembly has hit a piece of cartilage, and the surgeon may not be sure if he wants to go further. In some cases, when the end-effector assembly has hit something that blocks it from firing or that the motor drive has to overcome, the instrument draws excessive current which can be detected and measured. However, motor current measurements may not be entirely reliable, such as when the end-effector assembly has hit another staple line or encountered a malformed series of staples.